1. Field of the Invention
The present invention relates to an electrode for electrochemical capacitor and a method for manufacturing the same, and to an electrochemical capacitor and a method for manufacturing the same.
2. Related Background Art
Electrochemical capacitors represented by electric double layer capacitors are readily available in small size and light weight. Owing to the advantage, the electrochemical capacitors are expected, for example, as backup power source for handy equipment (miniature electronics equipment) and the like, auxiliary power source for electric cars and hybrid cars, and other power sources. Various studies have been given to improve the performance of these electrochemical capacitors. Particularly when large capacity is required as the power source of electric car and the like, there is wanted the development of electrochemical capacitors having high electrostatic capacity per unit volume of electrode, (hereinafter referred to as the “volume capacitance”).
The electrodes used in those types of electrochemical capacitors are fabricated by forming a porous body layer having electronic conductivity on a collector having electronic conductivity. The porous body layer is generally formed by applying a liquor containing porous particles, a conductive assistant, a binder, and a liquid onto the collector.
The conductive assistant as a component of the porous body layer is used mainly to give sufficient electronic conductivity to the porous body layer. The content of the conductive assistant in the porous body layer is conventionally in an approximate range from 10 to 20% by mass based on the total amount of the porous body layer. Subjecting to the content range, the content of porous particles and the content of binder have been adjusted to approximately from 20 to 80% by mass and from 5 to 40% by mass, respectively, (refer to, for example, JP-A-1-227417, (the term “JP-A-” referred to herein signifies the “Japanese Patent Laid-Open Publication”)). Furthermore, by adjusting the contents of respective components (porous particles, conductive assistant, and binder) in the porous body layer to further suitable range within the above-specified range, the volume capacitance of the electrode has been improved.